Method for treating the air in a display cabinet and display cabinet for carrying out said method

ABSTRACT

In a method for air treatment in a display cabinet for the storage and/or display of objects, whose walls, floor and roof structure more or less enclose the inside space of the display cabinet and in which a forced inflow of air from an air delivery system connected to the inside space ( 1 ) of the cabinet maintains a slight excess pressure compared with the air outside it, the said airflow passes through suitable dust or gas filtration means before entering the cabinet and its air humidity is adjusted and/or controlled by means of a cooling device. After filtration, the airflow passes into a container ( 2 ) holding a liquid ( 7 ), the said liquid being kept free from germs by suitable means. In this manner and in a simple way, a completely germ-free atmosphere is produced inside the display cabinet. A display cabinet for implementing the method has a corresponding structure.

The invention concerns a method for air treatment in a display cabinetfor the storage and/or display of objects, whose walls, floor and roofstructure more or less enclose the inside space of the display cabinetand in which a forced inflow of air from an air delivery systemconnected to the inside space of the cabinet maintains a slight excesspressure compared with the air outside it, this airflow passing throughsuitable dust or gas filtration means before entering the cabinet andhaving its air humidity adjusted and/or controlled, and a correspondingdisplay cabinet for implementing the method.

Such a method and a corresponding display cabinet are already known.Thus, DE-PS 38 05 212 C2 describes a cabinet for the storage and/ordisplay of objects, in which, for the protection of the objectsdisplayed, the air surrounding them inside the cabinet is kept not onlyfree from dust but also within a desired range of air humidity. It isalso possible to fill the inside space with a neutral gas, if this isrequired for the protection of the objects displayed.

Besides freedom from dust, controlled humidity, etc., the case can alsoarise that certain objects inside the display cabinet requiresurroundings free from germs.

Thus, the purpose of the present invention is to indicate a method ofthe type mentioned above, in which the airflow passing into the displaycabinet is rendered germ-free, and to supplement the equipment of adisplay cabinet of the type mentioned at the start, in such manner thata germ-free atmosphere is produced inside the cabinet.

With a method and equipment of the type mentioned earlier, theseobjectives are achieved by passing the airflow, after filtration, into acontainer holding a liquid and providing in the said liquid a catalyserby means of which the air is rendered completely free from germs.

Since even an airtight cabinet is never completely impervious to gas andalso, when it is opened, air from outside can enter the inside space,the maintenance of a slight excess pressure compared with the ambientair produces a flow of air from the inside outwards, with the resultthat clean, cooled and germ-free air has to be fed continuously into theinside space, whereby the air throughout the inside space of the displaycabinet is completely renewed over a period of a few days, depending onits size. In this way a completely germ-free atmosphere is achievedafter a certain time.

DE-PS 198 26 930 C2 describes a climate-controlled display cabinet, inwhich a flat heat exchanger is in the inside space of the cabinet and acollecting and humidifying tray is arranged under it, the heat exchangerbeing connected to a refrigerating machine. From the description it canbe seen that by means of a fan, a controlled flow of air can be passedthrough a number of cabinets connected in series. In contrast, in thepresent invention the controlled airflow first passes into a containerholding a liquid and then to a cooler.

The climate-control of a display cabinet is also the object of WO01/84986 A1, in which the air inside a display cabinet is propelledthrough a dehumidifying and heating/cooling device. The said devicecontains a hygroscopic medium, for example silica gel, which has to bereplaced as soon as it has absorbed too much water.

An air purification system in which germs are also removed from the airis described in DE-OS 199 03 022 A1, in which the air is treated by anelectrostatic device. Such a device is intended for use in many ways,such as in the air ducts of climate-control units in which the heated orcooled air is subjected to germ removal. The description does notmention how such germ removal is to take place in the case of displaycabinets. In contrast, in the present invention the air humidity of thealready germ-free air is adjusted and/or controlled in combination witha cooling device.

In collaboration with the liquid containing an additive, the catalyseraccording to the invention frees the air that has been brought intocontact with the liquid from germs.

Other advantages emerge from the subordinate claims relating to themethod and device according to the invention.

The invention will be explained in more detail with reference to twoexample embodiments illustrated in the drawing, which shows:

FIG. 1: Section through a container of liquid with a flat catalyser, and

FIG. 2: Section through a container of liquid with a sponge, which issurrounded by a catalyser

The container 2 shown in FIG. 1 is closed by a cover 10 and contains aliquid 7, for example distilled water. Into the headspace above theliquid 7 is passed an airflow 5 freed from the ambient air dust, forexample by passing through an appropriate filter. Above the liquid 7 theair picks up moisture, and the air so treated is passed into a coolingdevice 4 in which the humidity of this air is adjusted and regulated toa specified value. The air 6 treated in this way is then passed by meansof a pump (not shown) into the inside space of the display cabinet. Thepump serves to maintain a slight excess pressure in the inside space 1of the cabinet, and only has to deliver an amount of air sufficient tomake up for any air that escapes to the outside by leaking out of thecabinet. The cooling device 4 and the pump (not shown) are controlled bya control unit 3 to which sensors (not shown) for air pressure andhumidity positioned in the inside space 1 of the display cabinet areconnected, so that the pump is correspondingly controlled as a functionof the specified air pressure, and the cooling device 4 as a function ofthe specified air humidity. A monitoring device (not shown) for thefilling level of liquid 7 in the container 2 can also be connected tothe control unit 3, and by means of an acoustic and/or visual signalthis indicates when the liquid reserve in the container 2 should betopped up.

At the bottom of the container 2 in the liquid 7 there is a catalyser 8in the form of a flat grid held between the two flat surfaces ofrespective protective gratings 9, and it must be ensured that thecatalyser is covered by liquid 7 at all times.

FIG. 2 shows a second embodiment in which the dust-free airflow 5 ispassed into a sponge 11, the sponge 11 being enveloped by the grid ofthe catalyser 8. The humidified air escapes from the sponge 11 and risesto the surface of the liquid 7. The further treatment of the cleaned andhumidified air 6 then takes place in the manner already described. Thesponge must be covered by the liquid 7 at least sufficiently for thecatalyser 8 to be below the surface of the liquid 7.

The catalyser can take any form such as wire, sheet, chips or powder,which will ensure the presence of a sufficiently large active surfacearea. The alloy used for the catalyser consists of 10 to 80 mass-% ofcobalt, 5 to 50 mass-% of nickel, 5 to 20 mass-% of tungsten and 5 to 25mass-% of chromium, heat treated in an atmosphere containing oxygen for0.05 to 3 hours at temperatures in the range 250° to 1,250° C. Such acatalyser remains highly active for prolonged periods.

The collaboration of the catalyser 8 with water as the liquid 7 alreadyfrees the air in the inside space 1 of the display cabinet from germs.In particular cases when the objects on display in the cabinet so allowor require, the liquid 7 can for example also contain a certain amountof hydrogen peroxide.

The humidified and germ-free air is passed into the inside space 1 ofthe display cabinet, whereby the air surrounding the displayed objectsin the cabinet also becomes free from germs since after some time theair in the inside space 1 will have been completely renewed due toleaks, and the air can then be kept continually free from germs.

In the description of the two embodiments shown in FIGS. 1 and 2 It hasso far been assumed that the germ-free air is then passed into a coolingdevice 4 and thence to the inside space 1 of the display cabinet. It isalso conceivable, however, to pass the air first into a cooling device 4and only then to subject it to the treatment for germ removal. Dependingon the ambient temperature of the display cabinet, the cooling device 4can serve to adjust the air humidity and/or temperature of the air inthe inside space 1 of the cabinet, by heating or cooling the air. Inthis it is also conceivable, if the cooling device 4 is of appropriatedesign, i.e. when in accordance with the state of the art, incombination with water a specified air humidity and/or air temperaturecan be established, to combine the cooling device 4 with the deviceaccording to the invention for eliminating germs from the air, since thewater serves both to adjust the air humidity and/or temperature andalso, by virtue of the additive in combination with the catalyser, toeliminate germs from the air.

The air 5 treated to remove dust can all come from the air outside thedisplay cabinet, but it is also conceivable for some of this air to comefrom the inside space 1 of the cabinet, whereby the air replacement inthe inside space 1 is accelerated.

The devices described for humidifying and eliminating germs from the airin the inside space 1 of a display cabinet can be positionedindividually as closed units inside the cabinet. It is also conceivable,however, if there are several display cabinets, to provide a commondevice to which only the inside space 1 with the air duct(s) and withthe sensors is connected.

The invention can be used both for display cabinets in which objects areset out for display, and with cabinets serving only for the storage ofobjects.

1. Method for the treatment of air in a cabinet for the storage and/ordisplay of objects, whose walls, floor and roof structure more or lessenclose the inside space of the cabinet and in which a forced inflowfrom an air delivery system connected to the inside space of the cabinetmaintains a slight excess pressure compared with the air outside it,this airflow passing through suitable dust or gas filtration meansbefore entering the cabinet and having its air humidity adjusted and/orcontrolled, wherein after filtration the inflowing air (5) passes into acontainer (2) holding a liquid (7) and a catalyser (8) is present in theliquid (7), by means of which the air is completely free from germs. 2.Method according to claim 1, wherein the liquid (7) consists of water.3. Method according to claims 1, wherein the liquid (7) contains anadditive.
 4. Method according to claim 1, wherein the catalyser (8)consists of a wire grid made from a particular alloy.
 5. Methodaccording to claim 4, wherein the wire grid is made as a mat and is heldbetween two protective gratings (9) of at least the same size.
 6. Methodaccording to claim 1, wherein the airflow (5) is passed over the surfaceof the liquid (7) in the container (2)
 7. Method according to claim 4,wherein the airflow (5) is passed into a sponge (11) wetted by theliquid (7), which is enveloped by the wire grid.
 8. Method according toclaim 1, wherein the airflow (5) passing into the container (2) consistsof two parts, one part from the outside air and one part from the airinside the display cabinet.
 9. Method according to claim 1, wherein thegerm-free air passes into a cooling/heating device (4), which serves tomaintain a specified temperature and/or air humidity.
 10. Methodaccording to claim 1, wherein the airflow (5) first passes into acooling/heating device (4) which serves to maintain a specifiedtemperature and/or air humidity, and is then freed from germs. 11.Method according to claim 10, wherein the cooling/heating device (4)regulates the specified temperature and/or air humidity by means of aliquid, this liquid being identical to the liquid (7) of the catalyser(8).
 12. Display cabinet for implementing the method according to claim1, whose walls, floor and roof structure more or less enclose the insidespace of the display cabinet and in which a forced inflow of air from anair delivery system connected to the inside space of the cabinetmaintains a slight excess pressure compared with the air outside it,this airflow passing through suitable dust or gas filtration meansbefore entering the cabinet and having its air humidity adjusted and/orcontrolled, wherein after filtration the airflow (5) is passed into acontainer (2) holding a liquid (7) and in the liquid (7) there is acatalyser (8), by means of which the air subsequently passed to acooling device is rendered completely free from germs.
 13. Displaycabinet according to claim 12, wherein the liquid (7) consists of waterand contains an additive.
 14. Display cabinet according to claim 12,wherein the liquid (7) contains a certain amount of hydrogen peroxide.15. Display cabinet according to claim 12, wherein the catalyser (8)consists of a wire grid made from a particular alloy.
 16. Displaycabinet according to claim 15, wherein the wire grid is made as a matand is held between two protective gratings (9) of at least the samesize.
 17. Display cabinet according to claim 15, wherein a sponge (11)is enveloped A by the wire grid and the airflow (5) is passed throughthe sponge.
 18. Display cabinet according to claim 12, wherein theairflow (5) passing into the container (2) consists of two parts, onepart from the outside air and one-pain from the air inside the displaycabinet.